二维全同Nb_4团簇在Cu(100)表面的结构稳定性和电子性质

Structural stability and electronic properties of ordered identical Nb_4 clusters on the Cu(100) surface

使用基于密度泛函理论的第一性原理赝势法和超原胞模型,研究了吸附在Cu(100)表面上的二维有序排列的幻数团簇Nb4的结构稳定性及其电子结构性质.计算表明,四面体结构和平面的菱形结构的Nb4团簇都可以稳定地吸附在Cu(100)表面上,这个体系很可能有重要的应用前景.在Cu(100)表面上,菱形结构的Nb4比四面体结构的Nb4更稳定,从Nb4团簇的四面体结构到菱形结构,需经过的势垒高度约为0.94eV/团蔟.电子结构的计算表明,在Nb4吸附后,Cu(100)表面与Nb4团簇间有明显的电荷重新分布,表面Cu原子的电子态密度也明显改变.

First-principles density-functional theory and supereell models are employed to study the structural stability and electronic properties of the periodic two-dimensional arrays of identical Nb4 clusters on the Cu（100） surface. The total-energy calculations show that Nb4 clusters with both tetrahedron and quadrangle configurations can be stably absorbed on the Cu（100） surface, which might have important applications. The adsorption of quadrangular Nb4 clusters is shown to be more stable than that of tetrahedral Nb4. The energy barrier for the transition of tetrahedral Nb4 adsorption to the quadrangular one is around 0.94 eV/cluster. Electronic structure calculations suggest that adsorption of Nb4 on Cu（100） surface causes significant charge redistributions between the surface Cu layer and the Nb4 adsorbate leading to remarkable changes in the electronic structure of the copper surface.